User Board - Supporting Other Experiments

1. User Board - Supporting Other Experiments Stephen Burke, RAL pp Glenn Patrick

2. User Board • Meets ~ 3 times a year • Representatives of all experiments • Allocates CPU and disk at the Tier-1 • And in principle the Tier-2s • Also discusses any topics of interest to users • But not a technical forum, mainly about policy • “Once operational, the LHC experiments will obviously be the main strategic priority. However, all attempts will also be made to resource the non-LHC experiments within the limits of available funding.” • http://www.gridpp.ac.uk/eb/ UB – GridPP 23

3. Resources for non-LHC VOs • Small experiments seem to prefer to use the Tier-1 • So far the Tier-1 CPU has been under-utilised, but that may change when the LHC starts taking data • Storage can be allocated to small VOs in Castor, but it’s a complex and heavyweight system if you just want a few TB of disk storage • Needs discussion with the Tier-1 team to set up, and takes some time, so give notice well in advance • Disk server size gives a quantised allocation • Tier-1 team have to give priority to LHC experiments, but they do support everyone • Consider the Tier-2s too • Total resources are comparable to the Tier-1 • DPM Storage Element is much simpler than Castor • Grid model: jobs can run anywhere • Local support if you use your local site UB – GridPP 23

4. Other resources • VOMS server: maintained by Manchester • File Catalogue: can use the LFC at the Tier-1 • WMS (aka Resource Broker): primary at the Tier-1 • Other instances at Glasgow and Imperial • User Interface: should be one at your local site • UI at the Tier-1 is restricted, but access can be granted if it’s needed • GANGA: job submission and management tool • Developed in the UK for ATLAS and LHCb, but now widely used and supported • Documentation • GridPP web site: http://www.gridpp.ac.uk/deployment/users/ UB – GridPP 23

5. Support for small VOs • Janusz Martyniak: software/service support • Running an LFC • Support for use of VOMS, BDII, … • Gridification • Stephen Burke: documentation, advice, troubleshooting • Use of MyProxy • Use of SRM, lcg-utils etc • Middleware support and debugging • Pointers to documentation • Ask for help via UB or directly to us • New “startup” VOs need particular help to get started UB – GridPP 23

6. Other support channels • Two weekly meetings, both in EVO: • dteam, Tuesdays at 11 am • deals mainly with Tier-2 issues • Tier-1 weekly, Wednesdays at 13:30 • Both have slots for any experiment to discuss problems and requirements • GGUS tickets • To report specific technical problems with any Grid site or middleware • www.ggus.org • Training • Provided for EGEE (and EGI?) by Edinburgh (NESC) • Not sure if any GridPP users have tried it • Do we need something customised for small HEP VOs? UB – GridPP 23

7. Mailing lists • UKHEPGRID • General announcements, low volume • GRIDPP-USERS • Originally intended for user discussion, but never used in practice • Now used for user-oriented announcements • TB-SUPPORT • Discussion list for site admins • Fairly active, user questions would probably get a helpful answer • dteam • Internal list for the dteam, but users could address questions to it • GRIDPP-UB • UB mailing list, low volume discussion of resource/policy issues • http://www.gridpp.ac.uk/contact.html UB – GridPP 23

8. General comments • Please ask for help!!! • Sometimes people seem reluctant • The Grid has a reputation for problems – some justification for that but people may give up too easily • Need to follow up if things aren’t moving • Sites would like to know what’s happening, good or bad • Don’t just ask one person, they may be busy or not know the answer • It is possible to solve Grid problems … • … sometimes … • Or else there is usually another way – maybe not ideal but things can be made to work, many users are using the Grid successfully UB – GridPP 23

9. Random examples • “Maradona” error • Major cause of job failure since forever • Seems cryptic, hard to understand, people just ignore and resubmit • “The Grid is broken”! • There are several possible causes and it can take some effort to track down, but it can be fixed, it isn’t inevitable • GGUS ticket to site • “Can’t delete directories in SRM” • Technically possible, but there was indeed no easy way • Submitted a savannah bug, fix took a few months to get to production • Now you can do it (lcg-del –d) • Using MyProxy to automatically renew a VOMS proxy • Not obvious, but easy when you know how • Now documented: http://www.gridpp.ac.uk/deployment/users/myproxy.html UB – GridPP 23

10. Summary • LHC experiments are bound to get priority, especially as data-taking starts, but GridPP does support the other experiments too • UK CPU resources are substantial • A small fraction of a large system is still a lot • Scope for opportunistic use when LHC VOs are quiet • The original rationale for the Grid • Storage is harder because it’s long-term • But small experiments probably don’t need a huge amount • Consider Tier-2 as well as Tier-1 • Ask for help, it is available • Don’t give up! UB – GridPP 23

11. UK Grid usage UB – GridPP 23